It does not read like an endorsement — just an assessment that Yang's plan is better than a plan he describes as unworkable (Warren's).
In the Youtube, he says: "My own view is that a universal income financed by an efficient tax, something like a value added tax, might well be worth considering" — hardly a full-throated endorsement.
Has he said anything else that is more positive? Or more specific with regard to the amount of UBI that he thinks would be appropriate/efficient? I wouldn't call either of these things an endorsement.